1. Field of the Invention
The invention relates to an articulated suspension device in particular for support systems of electronic appliances such as e.g. monitors.
Suspension devices for support systems are currently used e.g. in the field of medicine. For every type of intervention, treatment, investigation or monitoring procedure carried out on a patient, the practitioner has at his disposal i.a. a wide variety of back-up functions, such as measuring, visualizing, lighting etc., that are realized by means of electronic appliances and/or systems. As these electronic appliances have to be variably positioned and aligned in dependence upon the position of the patient and the practitioner, the appliances are connected to a support system, which is fastened by an articulated suspension device realized e.g. by means of spring arms to the ceiling or to the walls of the room and may be aligned in a plurality of degrees of translatory and rotatory freedom within a limited range of motion. 2. Discussion of the Prior Art
In order to achieve the smoothest possible rotational and tilting movements over a wide rotational and tilting range in the joints of the suspension device, almost exclusive use is made of spherical or part-spherical ball joints. From the utility model DE 93 01 268 U1, for example, it is known for the articulated joint to comprise an interface component carrying a joint ball as well as a connecting flange containing a joint-ball bearing. The rotational and tilting movement of the ball joint is effected by a part-spherical sliding movement of the joint ball in the joint-ball bearing. Whilst the internal diameter profile of the joint-ball bearing corresponds to the part-spherical surface profile of the joint ball, the external diameter profile corresponding to the internal profile of the connecting flange has a purely cylindrical shape.
This geometric simplification, which reduces the outlay for manufacture and assembly of the ball-joint bearing, is however achieved at the cost of considerable mechanical drawbacks. As forces may be transmitted at contact surfaces between various components only in orthogonal direction to the surface, forces acting in the connecting flange are introduced, because of the cylindrical interfaces between connecting flange and joint-ball bearing, only at right angles to the lateral cylinder surface and/or at right angles to the cylinder bases into the joint-ball bearing. An introduction of force into the joint-ball bearing that is radially symmetrical and directed towards the centre of the joint ball, such as is effective at the transition from the joint-ball bearing to the joint ball because of the spherical interface, is not possible. A homogeneous introduction of force into the ball joint bearing and hence an optimum transmission of force to the joint ball that leads to a deflection of the joint ball proportional to the force originally acting upon the connecting flange is therefore not possible. Rather, the non-radial component of the force acting upon the joint-ball bearing that cannot be transmitted to the joint ball leads to an undesirable reaction of force at the contact surfaces between connecting flange and joint-ball bearing as well as at the fastening elements between both components. These undesirable reactions of force lead at the said points to component wear owing to compression-, extension- or friction processes.